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More than two years after an estimated 20-meter class meteor fragmented high over the Russian city of Chelyabinsk, new data reported by NASA researchers this week reveals that --- over a four billion year timeframe --- the meteor’s orbital parent body itself had likely been geologically-impacted as many as a dozen times.

Two 15- to 20-gram samples of the Chelyabinsk meteorite that NASA obtained from Russia over a year ago reveal a broad range of information about the meteor’s mineralogy, bulk composition and age, as noted at the Lunar and Planetary Science Conference in Houston.

These same fragments came off the path of the fireball somewhere around the middle of its trajectory through Earth’s atmosphere, Kevin Righter, the lead for meteoritic sample analysis and the Antarctic meteorite curator at NASA’s Johnson Space Center, told Forbes. He says the fragments --- pieces from the outer portion of the meteor itself which streaked across the Russian sky on February 15, 2013 --- are typical of more stony-type meteorites and made up of some 90 percent silicate; five percent sulfide; and five percent iron-nickel.

The original crystallization age of the parent body asteroid, says Righter, might be 4.5 billion years old. But in this case, he says, they found multiple ages using three or four different chronologic detection techniques.

Righter says he and colleagues found evidence for about a dozen different parent-body impact events in pieces of the Chelyabinsk meteorite they studied; ranging from 300 million years ago to as recently as 27 million years ago.

People look at what scientists believe to be a chunk of the Chelyabinsk meteor, recovered from Chebarkul Lake near Chelyabinsk, about 1500 kilometers (930 miles) east of Moscow, Russia, Wednesday, Oct. 16, 2013. Scientists on Wednesday recovered what could be the largest part of this meteor from Chebarkul Lake outside the city. They weighed it using a giant steelyard balance, which displayed 570 kilograms (1,256 pounds) before it broke. (AP Photo/Alexander Firsov)

“Geologically, that’s very young,” said Righter. “Ages determined on ordinary chondrites can be as old as over 4 billion years old. But there’s hardly ever any evidence for these young ages.”

The meteor, which initially exploded in the Russian atmosphere at some 29 km in altitude, wreaked widespread destruction and injury in and around the city of Chelyabinsk. But how much of the Chelyabinsk meteoritic material actually made it to the ground?

The main so-called “terminal mass” of the asteroid was a couple of meters in diameter and weighed over 500 kilograms, planetary scientist Paul Abell, also at NASA’s Johnson Space Center, told Forbes.

What hope do we have of actually identifying the parent body of this Chelyabinsk object in the near-Earth vicinity?

Finding the parent body of a near Earth asteroid, says Abell, is “really tough” because these asteroids are in chaotic orbits. “The best we can do,” he said, is to try and make a compositional link.

“The parent body undoubtedly came from the Main Asteroid Belt, the question is how the Chelyabinsk piece got into near-Earth orbit,” said Abell. “Was it directly transferred from an impact event on a main parent body and then transferred directly to Earth-crossing orbit, or was it a piece of another near-Earth asteroid that broke off?”

Overall, says Righter, it has the same composition as the LL chondrite group, a subgroup of stony asteroids known to contain both low iron and low metal.

“Knowing it’s an LL chondrite narrows the field a bit, but there are a lot of these chondrites in the near-Earth asteroid population,” said Righter. “We also have a lot of LL chondrite material in our collections, but we don’t know where they came from because most were found serendipitously without any [data] on their orbits or timing of fall.”

But the hope is that such continuing analysis will enable researchers to make a genetic compositional link between meteoritic samples in curated Earth-based collections and potential near-Earth asteroidal impactors lurking in our vicinity.

“The last three big meteor events in history have been over the Russian mainland,” said Abell. “It’s not because asteroids have an agenda against the Russian people, it’s just that in comparison to Earth’s oceans, Russia is the next biggest thing to hit.”

But as Abell points out, researchers now have a plethora of new atmospheric fireball and meteor detection methods at their disposal.

NASA and other U.S. Government agencies have better sensors that now help look at such high altitude events, says Abell. He notes that there are also more dash cams and security cameras and cell phone cameras; including cell phone apps, capable of easily filing reports of these bolides to a central office.

Have we underestimated the threat from near-Earth asteroids?

We have a pretty good understanding of where 95 percent of the near-Earth asteroids (one km in diameter and up) actually are, says Abell. But, he says, surveys of near-Earth objects of 100 meters or less are not even one percent complete.

“We used to think that a 20 meter-sized meteor wasn’t that big a threat,” said Abell. “But the Chelyabinsk meteor was only 20 meters and we saw what it could do.”